@@ -278,6 +278,7 @@ void address_space_init_once(struct address_space *mapping)
spin_lock_init(&mapping->private_lock);
INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
+ INIT_LIST_HEAD(&mapping->unpinned_list);
}
EXPORT_SYMBOL(address_space_init_once);
@@ -47,6 +47,9 @@
#define MADV_HUGEPAGE 14 /* Worth backing with hugepages */
#define MADV_NOHUGEPAGE 15 /* Not worth backing with hugepages */
+#define MADV_VOLATILE 16 /* _can_ toss, but don't toss now */
+#define MADV_ISVOLATILE 17 /* Check if page is marked volatile or not */
+#define MADV_NONVOLATILE 18 /* Remove VOLATILE flag */
/* compatibility flags */
#define MAP_FILE 0
@@ -632,6 +632,33 @@ int pagecache_write_end(struct file *, struct address_space *mapping,
loff_t pos, unsigned len, unsigned copied,
struct page *page, void *fsdata);
+
+
+/* upinned_mem_range & range macros from Robert Love's Ashmem patch */
+struct unpinned_mem_range {
+ struct address_space *addrsp; /* associated address_space */
+ struct list_head unpinned; /* Next unpinned range */
+ size_t start;
+ size_t end;
+ unsigned int purged;
+};
+
+#define range_size(range) \
+ ((range)->end - (range)->start +1)
+#define page_range_subsumes_range(range, start_addr, end_addr) \
+ (((range)->start >= (start_addr)) && ((range)->end <= (end_addr)))
+#define page_range_subsumed_by_range(range, start_addr, end_addr) \
+ (((range)->start <= (start_addr)) && ((range)->end >= (end_addr)))
+#define page_in_range(range, page) \
+ (((range)->start <= (page)) && ((range)->end >= (page)))
+#define page_range_in_range(range, start_addr, end_addr) \
+ (page_in_range(range, start_addr) || page_in_range(range, end_addr) || \
+ page_range_subsumes_range(range, start_addr, end_addr))
+#define range_before_page(range, page) \
+ ((range)->end < (page))
+
+
+
struct backing_dev_info;
struct address_space {
struct inode *host; /* owner: inode, block_device */
@@ -650,6 +677,7 @@ struct address_space {
spinlock_t private_lock; /* for use by the address_space */
struct list_head private_list; /* ditto */
struct address_space *assoc_mapping; /* ditto */
+ struct list_head unpinned_list; /* unpinned area list */
} __attribute__((aligned(sizeof(long))));
/*
* On most architectures that alignment is already the case; but
@@ -225,6 +225,168 @@ static long madvise_remove(struct vm_area_struct *vma,
return error;
}
+
+
+static int unpinned_range_alloc(struct address_space *addrsp,
+ struct unpinned_mem_range *prev_range,
+ unsigned int purged, size_t start, size_t end)
+{
+ struct unpinned_mem_range *range;
+
+ range = kzalloc(sizeof(struct unpinned_mem_range), GFP_KERNEL);
+ if (unlikely(!range))
+ return -ENOMEM;
+
+ range->addrsp = addrsp;
+ range->start = start;
+ range->end = end;
+ range->purged = purged;
+
+ list_add_tail(&range->unpinned, &prev_range->unpinned);
+
+ return 0;
+}
+
+static void unpinned_range_del(struct unpinned_mem_range *range)
+{
+ list_del(&range->unpinned);
+ kfree(range);
+}
+
+static inline void unpinned_range_shrink(struct unpinned_mem_range *range,
+ size_t start, size_t end)
+{
+ range->start = start;
+ range->end = end;
+}
+
+
+static long madvise_volatile(struct vm_area_struct * vma,
+ unsigned long start, unsigned long end)
+{
+ struct unpinned_mem_range *range, *next;
+ unsigned int purged = 0;
+ int ret;
+ struct address_space *addrsp;
+
+ /* XXX - check start->end is within mmapped shm region */
+ if(!vma->vm_file)
+ return -1;
+
+ addrsp=vma->vm_file->f_mapping;
+
+
+ start -= vma->vm_start;
+ end -= vma->vm_start;
+
+ printk("Madvise_volatile: start: 0x%lx end: 0x%lx vma start: 0x%lx\n", start, end, vma->vm_start);
+
+restart:
+ list_for_each_entry_safe(range, next, &addrsp->unpinned_list,
+ unpinned) {
+ if (range_before_page(range, start))
+ break;
+
+ if(page_range_subsumed_by_range(range, start, end))
+ return 0;
+ if (page_range_in_range(range, start,end)) {
+ start = min_t(size_t, range->start, start);
+ end = max_t(size_t, range->end, end);
+ purged |= range->purged;
+ unpinned_range_del(range);
+ goto restart;
+ }
+
+ }
+ ret = unpinned_range_alloc(addrsp, range, purged, start, end);
+ return ret;
+}
+
+static long madvise_nonvolatile(struct vm_area_struct * vma,
+ unsigned long start, unsigned long end)
+{
+ struct unpinned_mem_range *range, *next;
+ int ret = 0;
+ struct address_space *addrsp;
+ if(!vma->vm_file)
+ return -1;
+ addrsp=vma->vm_file->f_mapping;
+
+
+ start -= vma->vm_start;
+ end -= vma->vm_start;
+
+ list_for_each_entry_safe(range, next, &addrsp->unpinned_list,
+ unpinned) {
+ if (range_before_page(range, start))
+ break;
+
+ if (page_range_in_range(range, start, end)) {
+ ret |= range->purged;
+ /* Case #1: Easy. Just nuke the whole thing. */
+ if (page_range_subsumes_range(range, start, end)) {
+ unpinned_range_del(range);
+ continue;
+ }
+
+ /* Case #2: We overlap from the start, so adjust it */
+ if (range->start >= start) {
+ unpinned_range_shrink(range, end + 1,
+ range->end);
+ continue;
+ }
+
+ /* Case #3: We overlap from the rear, so adjust it */
+ if (range->end <= end) {
+ unpinned_range_shrink(range, range->start,
+ start-1);
+ continue;
+ }
+
+ /*
+ * Case #4: We eat a chunk out of the middle. A bit
+ * more complicated, we allocate a new range for the
+ * second half and adjust the first chunk's endpoint.
+ */
+ unpinned_range_alloc(addrsp, range,
+ range->purged, end + 1,
+ range->end);
+ unpinned_range_shrink(range, range->start, start - 1);
+
+ }
+
+ }
+
+ printk("Madvise_nonvolatile: start: 0x%lx end: 0x%lx vma start: 0x%lx ret: %i\n", start, end, vma->vm_start, ret);
+ return ret;
+
+
+}
+
+static long madvise_isvolatile(struct vm_area_struct * vma,
+ unsigned long start, unsigned long end)
+{
+ struct unpinned_mem_range *range;
+ long ret = 0;
+ struct address_space *addrsp;
+ if(!vma->vm_file)
+ return -1;
+ addrsp=vma->vm_file->f_mapping;
+
+ start -= vma->vm_start;
+ end -= vma->vm_start;
+
+ list_for_each_entry(range, &addrsp->unpinned_list, unpinned) {
+ if (range_before_page(range, start))
+ break;
+ if (page_range_in_range(range, start, end)) {
+ ret = 1;
+ break;
+ }
+ }
+ return ret;
+}
+
#ifdef CONFIG_MEMORY_FAILURE
/*
* Error injection support for memory error handling.
@@ -268,6 +430,12 @@ madvise_vma(struct vm_area_struct *vma, struct vm_area_struct **prev,
return madvise_willneed(vma, prev, start, end);
case MADV_DONTNEED:
return madvise_dontneed(vma, prev, start, end);
+ case MADV_VOLATILE:
+ return madvise_volatile(vma, start, end);
+ case MADV_ISVOLATILE:
+ return madvise_isvolatile(vma, start, end);
+ case MADV_NONVOLATILE:
+ return madvise_nonvolatile(vma, start, end);
default:
return madvise_behavior(vma, prev, start, end, behavior);
}
@@ -293,6 +461,9 @@ madvise_behavior_valid(int behavior)
case MADV_HUGEPAGE:
case MADV_NOHUGEPAGE:
#endif
+ case MADV_VOLATILE:
+ case MADV_ISVOLATILE:
+ case MADV_NONVOLATILE:
return 1;
default:
@@ -679,6 +679,26 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
index = page->index;
inode = mapping->host;
info = SHMEM_I(inode);
+
+ if (!list_empty(&mapping->unpinned_list)) {
+ struct unpinned_mem_range *range, *next;
+ printk("shmem_writepage:\n");
+ list_for_each_entry_safe(range, next, &mapping->unpinned_list,
+ unpinned) {
+ printk(" range: 0x%lx - 0x%lx vs 0x%lx\n",
+ range->start, range->end,
+ (long)page->index << PAGE_SHIFT);
+
+ if (page_in_range(range,
+ (long)page->index << PAGE_SHIFT)) {
+ range->purged = 1;
+ unlock_page(page);
+ printk(" Purged page!\n");
+ return 0;
+ }
+ }
+ }
+
if (info->flags & VM_LOCKED)
goto redirty;
if (!total_swap_pages)
This patch provides new madvise flags that can be used to mark memory as volatile, which will allow it to be discarded if the kernel wants to reclaim memory. This is very much influenced by the Android Ashmem interface by Robert Love so credits to him and the Android developers. In many cases the code & logic come directly from the ashmem patch. The intent of this patch is to allow for ashmem-like behavior, but embeds the idea a little deeper into the VM code, instead of isolating it into a specific driver. Also many thanks to Dave Hansen who helped design and develop the initial version of this patch, and has provided continued review and mentoring in the VM code. Signed-off-by: John Stultz <john.stultz@linaro.org> --- fs/inode.c | 1 + include/asm-generic/mman-common.h | 3 + include/linux/fs.h | 28 ++++++ mm/madvise.c | 171 +++++++++++++++++++++++++++++++++++++ mm/shmem.c | 20 +++++ 5 files changed, 223 insertions(+), 0 deletions(-)